Subaqueous audible signaling apparatus.



S. lVL DAVISON.

SUBAQUBOUS AUDIBLB SIGNALING APPARATUS.

APPLICATION FILED APR. 13, 1914.

Patented D80. 22, 19M.

"il lllvllilv GFF.

SIDNEY MITCHELL DAVISON, OF LONDON, ENGLAND, ASSIGNOR 'TO MARCONIS WIRE- LESS TELEGRAPI-I COMPANY LIMITED, OF LONDON, ENGLAND.

SU'BAQUEOUS AUDIBLE SIGNALING APPARATUS.

Application filed April 13.

To all whom. it may cof/wem Be it known that I, Sinner MiiCHiiLL Davison, a citizen ot the United States of America, residing at London, in England, have invented certain new and useful Improvements in Subaqueous Audible Signal-v ing Apparatus, of which the `tolloiving is a specification,

rThis invention relates to improvements in subaqueous audible signaling apparatus, and consists in the use in a receiving device, including an electric transmitter, of certain solid materials other than metals` Woods, granite, stone, glass or the like, such materials including mineral and other waxes, resin, tallovv, beeswax, pitch, stearin, spermacetti, shellac, and similar materials, the latter materials being nfood or fairly elflcient conductors of sound as compared with water, and being solidified at average atmospheric temperature. Such substances have as compared with metals a comparativelyY low melting point, and should preferably have a specic gravity (density) near that ot' water (viz. higher than air and other gases and loiver than the metals, etc.). I also prefer to use a solid that is a non-con ductor of electricity and antipathic to Water. Submarine signal receiving apparatus, to be efficient for navigational purposes, must allovv an observer to hear the submarine hell at a considerable distance when the dynainos, pumps or engines are running, and I have discovered that a solid may be used provided the electric transmitter is not in relatively high conductive connection with the hull ot a steamer.

Solids having an elasticity and specific. gravity approximating that of Water are preferable, and I propose to use paratlin Wax, its specific gravity being approximately between .S7-l and .9 as compared With l of water, andthe speed of sound in a rod of this material is about 4700 feet per second at a temperature of 63 F., approximating the average velocity of sound in Water. The amount 'of reflection and the amplitude of the retractedray depend upon the elasticity (sound conducting quality) and density of the tWo media there vvill thus be practically no loss of energy in the use ot this material as compared with Water, and the Wax hasl other desirable qualities which render it incomparably superior to Water.

The use of a suitable solid such as paraffin- Specification of Letters Patent.

Patented Dc. 22, i914..

1914. SCU-.a1 N0. 831,574.

wax overcomes diiculties caused firstly by the leakage of Water or other liquid contained in a receiving vessel Within a ship whereby if-tlie liquid leaks to any great extent the receivers become either inoperative or inetlicient depending upon the degree of leakage, and secondly a microphonel submerged in liquid Will in time become grounded through leakage of the liquid or moisture into the chambei' containing the carbon transmitter, and when this occurs 'the elliciency of said transmitter becomes impaired to an extent dependent upon the extent of leakage and upon the amount of salt contained in the Water (salt rendering vatei'` as is Well knovvn, a good conductor of electricity). In some cases the transmitter may become entirely inoperative from this cause. In extremely cold climates the Water freezes and will destroy the electric transmitter if itis left in said Water; and if taken out the apparatus is rendered. inoperative.

As parain ivax is moisture proof, a nonconductor of electricity, and a solid at ordinary temperatures, its advantages over liquids at once become ap arent, when its density and sound conducting qualities are taken into consideration.

It is not desirable to use a telephonie transmitter mounted on metal or Wood which is part ot the hull ot' the ship, or that has contact with any solid material of high sound conductive qualities, because the noises produced by engines, pumps, or otherwise, within the ship, tend to or actually overcome the signal sounds (.Whether or not there has been any attempt to tune the transmitter) to an extent dependent upon the distance from the signal, or the intensity of same.

The longitudinal vibrations in the hull of a ship, caused by engine noises etc. do not have so great a tendency to affect materials in contact with the hull when said materials are both loiver in specific gravity and less ellicientin sound conducting qualities than said hull, this being true as regards Water and other comparatively light liquids, but the disadvantages of water or liquids have already been dealt with.

I prefer to use a Wax, or other suitable material as specified, having good sound conducting qualities and of high specific gravity (comparatively speaking) and I may coinbine certain'of said materials. Itv-is desirable to use a substance ot a waxy nature,

A such as paraffin wax, which will have a sufcient adhesiveness to remain attached to the skin of the ship, etc. in order that the conducting medium will not be broken; which might occur with the use of a hard, brittle material. Rubber, aspring or other means may be used for maintaining pressure on the paraiin wax to cause it to press against the ships lating. y

If rubber is used or sound insulating purposes it will be necessary to protect it 1f an material is used in the receiver which w11 chemically attacksame; the'method to depend upon the chemical action of the Inaterial used.

A further feature of the invention is in so arranging the telephonie transmitter that the heaving of a ship in a rough sea does not alter, at least to any degree, the Water pressure on the diaphragm of the telephonie transmitter this being accomplished by embedding the telephone transmitter or its containing case, in the paraiiin wax or other specified solid, or by introducing a second diaphragm exposed directly to water, or by a combination of both these means. The heaving of the ship alters the sensitiveness of the microphone when its diaphragm is directly exposed to the water and direction canv not therefore be ,accurately ascertained. I'propose vto use any type of electric'telephonic transmitter and this covers inertia, solid back or any other type, and they may be supported in `a case, the latter 'sembedded in wax; the wax may be poured used, the size of the vesesl &c.

entirely around the transmitter and against the diaphragm, or the transmitter may be in a metallic case and the .latter insulated from the former by rubber or other suitable means, or any other design or disposal found suitable; the method of arranging themicrophone will depend to a large extent under what, conditions they are to be I generally find is preferable to have the solid matter in contact with the diaphragm of a solid back type transmitter if the yreceiver is to be used when the ships engines are running. I also contemplate the use of microphone transmitters including .a diaphragm of deiinite pitch, which would not become altered if the transmitter case is embedded in the wax and were so arranged that the diaphragm was allowed to remain in free air. This would allow of using a- 'very sensitive transmitter specially useful for obtaining long distance signals when a ship is stopped.

It is believed that the volume of sound received depends upon the area of the receiver in contact with the hull of the ship and this may be made very` large when parain wax is employed. This is impracticable when water or other liquid is employed, owing to the difficulty and expense of making and keeping joints water-tight, but with paralin wax a' wooden container will suilice.

The accompanying drawings illustrate embodiments of mea-ns'suitable for carrying out the invention, Figures l and 2 being sections of two different or alternative forms of construction of receiving devices for the signaling apparatus.

Referring to Fig. 1, which shows one method of carrying outfthe-invention with the use of the wax orl other materials above suggested or mentionedI provide a shell a preferably of metal (althoughwhere a very.l

or material, one of such being shown, elec-` trically connected as by wires d1 to a telephone receiver, or otherreceiving device (not shown) on the bridge of the vessel or at other suitablelocation. The 'wax may be held in close contact with the hull by a "so I bracket e between which and the shell is ay I 'rubber block or gasket f for insulating said'l shell from internal' ships noises through said bracket. e, but .it 'is not intended that this invention shall be construed as vbeing limitedto these means, as any other appro# v priate devices may be adopted. As shown in this figure, the shell which protectsthe wax from destruction and secures same in place is filled with the wax for a distance slightly beyondthe outer edge of the latter in order to leave a space g between the shell and the ships hull to lavoid direct ,contact between said shell and hull, this space also serving as shown for passage of the wires from the transmitter.

Fig. 2 of the accompanying drawings shows a second method of applying the 1n'- vention to receivers on board ship, where signals over extreme distancesl are desired or required, such as on naval ships and large ocean going passenger Steamers, and is a very important feature of the invention. In

this method I remove a portion of the ships hull or plating, of moderate size, as at a, (or provide a `number of holes of small diameter) and provide a strong metal casing or receiver la, .against the inner side of the hull over said removed portion or portions, said receiver bein strongly constructed and either attached directly to the hull or insulated from same by rubber or other gasn kets. In the construction killustrated in the drawin .a gasket h1 as of canvas soaked in red lea is inserted between the hull and the ange h2 of the receiver, the latterA being se'- cured t0 the hull by bolts i countersunk intoY land hold the container k for a the latter, extending through said flange .and secured on the inside by lock nuts il.

Around the'aperture z inthe ships hull is a sleeve h3 of rubber or other sound. .insulating material (which also prevents electrolytic action between the .iron hull and gun metal cnntainerlareferred tov below.) secured in place by a clamping ring y' screwed into. .thethreaded interior of the receiver, the said sleeve being so shaped as toreceive ermanent portion of wax c which is 'flush or'sub'stantially so with the outer face of the hull, the container k having a ring, iange or equivalent k1 or other means to assist in holding the wax in position. There may be provided over the outer face of the metal container c and in contact with the wax a thin metallic high pitchor tension diaphragm Z to prevent undue wearof the wax by water friction, but 1 may dispense with this if required.

IfThe clamping ring j and the rubber in sulation h3 should be secured together so that the insulation metal container ,7c and wax portion c will. be removedtogether .when said is unscrewed. The aforesaid vclan'lping'ring j also serves to hold the permanent portion of wax c in place through its container la, and to the rear of said pervmanent kportion there is provided a shell m of. rubber or other appropriate material also containing wax c1 in which is embedded the transmitter d, this shell being secured by a second clamping ring jl screwed into the receiver h. This rin'g 9'1- having a short sleeve portion 7'3 embracing the rubber shell m, so. that the latter may be easily removed. The rings are shown as provided with holes 7'2 for reception of a tool for screwing thein in place. The rubber shell m containing the .transmitter is thus capable of being readily removed to inspect said transmitter or insert one of an improved or different type, or for other purpose. The wires d1 from the transmitter -are shown as passing through the'sidej of the receiver z. through an appropriate gland or equivalent h4.

Y With this type of apparatus Inlay provide the receiver z, with a gate valve fn. large enou h to allow of the insertion of the telephonic transmitter, and the material c1 in which it is embedded. This valve could be bolted as at nl to the back of the receiver and there would be no more. danger from leakage than with the ordinary sea-valves or the like commonly us'ed on board vessels. This valve can be mounted permanently in position or mounted only when the wax containin .the transmitter is to be withdrawn, and w en removed the blank flange or plate n2 can be bolted to the ianges of the receiver h when the apparatus is not. under-l going overhaul or inspection. There should be ,suiicient space between the valve gate n and the blank fiange n2 mounted in the valve to allow for; the convenient withdrawal of the wax containers, so that the gate valve can beshut down `when the parts are moved tosthe .backlo the valve space. There `will also be a stuffing box in the flange to take a key wrench for the-holes i2. The receiver could also be held against the hull by insulated angle irons or other means than Vthose shown, and it might also be of advantage to provide a second strong metal casing (not shown) firmly secured to the ships hull, but not in direct contact with' the sound lreceiving Y casing h, so that a vacuum, or insulating gas chamber, is provided between said two casings. A)In this double casing construction suitable removable covers should be provided to allow the microphones tobe removed from the inner casing, or sufciently large to remove the entire inner casing. This construction will be readily understood without illustration or further description.

V. A drip-cock o may beprovided on the c'asi'ngih, or on both where an outer casing is-provided, in order that a .test for leakage could be made .before takinga cover oil'. When using this installation 1t would prob ably be desirable to use a wax or substance be `011e means of eiiecting this purpose.

-An important advantage of having the wax in dlrect contact with the water would be that owing tothe sound conducting medium in the receivers consisting of a material having a specific gravity (or density) and possessing sound conducting qualities, approximating that of the exterior water, the loss of sound from the signal by retlection would be negligible as compared with that caused by the Asound vibrations having to traverse steel or iron, the theoretical critical angle for sound waves from water to steel being about 16-15 degrees and from water to paraiiin almost 90 degrees taking 63 degrees for the water temperature and as the specific gravity is .9 compared with l for f'water, the amplitude of the refracted ray will about equal the amplitude in the water itself. The great advantage when the sound producing device is ahead or bearing a few points on the bow is thus obvious. The pin diaphragm Z would probably decrease the critical angle somewhat, but one. of .suitable thickness (being say .04 inches thickness and under' tension) and pitch ought not to have a very detrimental eect, and the intensity of said sound vibrations reaching the transmitting apparatus would be considerably increased over that received by an internal receiver pressed against the plating. The rubber k3 and m insulates the container from the engine noises. l l

` By embedding the transmitter in the wax or other material as described, change of pressure in the vexternal water does not cause a change of pressure in the diaphragm of said transmitter and therefore tends to exclude any liability of the direction of the signal being incorrectly determined.

A still further type of apparatus 1s one suitable for overboard use, that is, the entire receiving apparatus submerged'in the water. The transmitter would be suitably incased so that the water would not cause a change of pressure on the diaphragm and could not leak into the containing casing. This type would allow of the use of a microphone of very sensitive design, and the diaphragm could be used in free air so that there wouldbe no damping effect, or change of pitch, and restraint from free movement, so that signals over greater distances could be obtained than is possible with other types of receiver. This would be especially desirable for use in warships and submarines while at anchor or not under way, to detect the approach of an enemys ship, or distant signals from one of their own ships.

It is intended'that this invention shall cover the use of all waxes and other materials specified in all applications to any vtype of submarine signal receiving appratus, for example, on board ship, whether they are entirely within the ship. exposed through the plating or ush with the outside of the hull, entirely overboard or otherwise, or other applications wherein the' sound conducting quality of the material," and its specific gravity, are the prime factors.

What I claim as my invention and desire to secure by Letters Patent of the United States is l. In a subaqueous audible signal receiving apparatus, an electric transmitter disposed out ot high conductive connection with the hull of the vessel in which it is located, and a receiving medium in conductive connection with said transmitter and with. the water in which the vessel float-s, consisting of a substance solid at ordinary temperatures and of comparatively low melting point. A

2. In a subaqueous audible signal recgiiv ing apparatus, an electric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, and a receiving medium in conductive connection with said transmitter and with lwith the hull of the vessel in which it is located, and a receiving medium in conductive connection with said transmitter and with the water in which the vessel floats, said re ceiving medium consisting of a subst-ance solid at ordinary temperatures and of comH paratively low melting point and having a sound conductive quality approximating that of Water.

4. In a subaqueous audible signal receiving apparatus, an electric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, and a receiving medium in conductive connection with said transmitter and with the water in which the vessel lloats, said receiving medium being a substance which 'is solid at ordinary temperatures and of comparatively 10W melting point, having a sound conductive qualityv less than or not greatly exceeding that of water, and being antipathic to the latter.

5. In a subaqueous audible signal receiving apparatus, an electric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, and a receiving medium in conductive connection Withsaid transmitter comprising a wax disposed in conductive connection with the water in which the vessel oats.

6. In a subaqueous audible signal receiving apparatus, an electric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, and a receiving medium in con-v ductive connection with said transmitter comprising parain Wax disposed in conductive connection with the water in which the vessel floats.

7. In a subaqueous audible signal receiving apparatus, thecombination of an electric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, and with the Water in which the vessel i'loats, and a sound receiving medium in which said transmitter is embedded consisting of a substance solid at ordinary temperatures, ot' comparatively low meltingpoint and having a sound conduct-ive quality less than .or not greatly eri-- ceeding that of water.

S. In a subaquous audible sional receiving apparatus, the rcombination of an elec tric transmitter, disposed out of high conductive connection with the hull of the vessel in which it is located, and a sound receiving medium in which said transmitter is embedded consisting of paraffin wax.

9. A subaqueous audible signal receiving apparatus adapted for use on board ship, comprising a protecting or insulating casing accessible from Withinthe ship, an electric telephone' transmitter out of high conductive connection with the hull of the vessel in which the apparatus is located Within said casing andhaving a diaphragm, means whereby the transmitter may receive sound vibrations from without the ship, without passing through any thick plating, a sound receiving medium in conductive connection,

. with said transmitter comprising a substance solid at ordinary temperatures and of comparatively low' melting point, and a tensioned metallic diaphragm other than that of the telephone transmitter in contact With the sound receiving medium whereby change of pressure in the external water fails to cause a material change ofpressure in the transmitter diaphragm.

10. In a subaqueous audible signal receiving apparatus, the combination of an elec-A tric transmitter disposed out of high conductive connection with the hull of the vessel in which it is located, a permanent portion of sound -receiving medium solid at ordinary temperatures and of comparatively low melting point in conductive contact with the water in which th vesselgsa floats, and a removable portion of said sound receiving vmedium in which said transmitter is embedded normally in contact with said permanent portion of the receiving Imedium.

11. In a subaqueous audible signal receiving apparatus, the combination of an electric transmitter disposed out of high conductive connection with the hull of the vessel or equivalent in which itis located, the 4 5 In witness whereof I have signed this 55 specification in the presence of two witnesses. I

SIDNEY MITCHELL Davison..

Witnessesz" A. J. HADDAN, H. P. VERM. l 

